I. Field of the Invention
This invention relates generally to medical apparatus for diagnosing and treating abnormalities in internal body organs, and more particularly to a flexible endoscope used in combination with a rigid introducer for more readily gaining access to the site within the body to be viewed and treated.
II. Discussion of the Prior Art
Many forms of endoscopes are known in the art. They generally comprise an elongated multi-lumen tube having a proximal end and a distal end. Included among the plural lumens is one containing an optical fiber or bundle of such fibers for transmitting light from a light source coupled to the proximal end of the tube to the distal tip for illuminating the vessel or organ cavity to be examined. Another lumen is typically used to contain a further optical fiber for transmitting the illuminated image to an eye piece or other viewing device coupled to the proximal end of the endoscope. An endoscope will further typically include a lumen comprising the working channel through which flushing liquid may be injected and aspirated and that working channel may also provide a pathway through which other instruments may be passed through the body to the location where the treatment is to be effected.
The tube comprising the endoscope may be rigid as in U.S. Pat. No. 4,986,258 to Cho et al. assigned to the Candela Laser Corporation of Wayland, Massachusetts, or, alternatively, may comprise a flexible tube as in the Foerster et al. U.S. Pat. No. 4,905,667. Rigid endoscopes are appropriate only when the passageway through the body is straight or linear while flexible endoscopes can be used in traversing a more tortuous path. There are medical procedures, however, where a rigid endoscope has advantages as regards certain aspects thereof while the flexible properties of a flexible endoscope may also prove advantageous for other phases of that procedure.
For example, when conducting an examination or treatment in the kidneys, an endoscope must be routed through the urethra, across the bladder, into the ostia of one or the other of the two ureters, through the selected ureter into the right or left kidney. Typically, the endoscope may be used to view kidney stones and then an appropriate instrument may be routed through the working channel of the endoscope to fragment or capture a stone to be removed. While a flexible endoscope may be readily passed through the urethra, it proves difficult to thread the flexible tube across the expanse of the bladder and then manipulate the flexible end into the desired ureter ostium. In this phase of the procedure, a rigid endoscope proves more workable because it can span the bladder without sagging. Thus, the device as described in the above-referenced Cho et al. Patent allows a physician to more readily position the distal or viewing end of the endoscope into a ureter. However, because of the curvature of the ureter proximate the pubic arch, it is most difficult to advance a rigid catheter beyond that point and into the kidney. In fact, because of the limitations placed upon the wall thickness of the rigid catheter by the dimensions of the tubular body passages to be traversed (the urethra and ureter) and the sizes of the lumens required in the endoscope for illumination, imaging and working, it has happened that rigid endoscopes have actually fractured when an attempt is made to traverse the curved portion of the ureter with that rigid instrument.
It can be appreciated, then, that neither a rigid nor a flexible endoscope is suitable for all phases of certain endoscopic procedures.